Hot steel slabs are commonly conditioned by positioning scarfing units along the top, bottom, and side surfaces of an advancing slab to eliminate surface defects such as cracks, seams, and slag intrusions. One conventional scarfing apparatus includes top, bottom, and opposite side scarfing units that are mounted across the width and end portions of a support, to concurrently scarf all sides of the slab as the slab is passed therebetween.
The top, side, and bottom scarfing units each include a gas distribution manifold, which receives and distributes oxygen, fuel gas, and cooling water to a number of scarfing units which are positioned in a side by side arrangement along the front of the manifold. As illustrated, for example, in U.S. Pat. Nos. 4,115,154 and 5,234,658, each scarfing unit comprises upper and lower preheat blocks which are spaced from each other to define an oxygen scarfing slot between the two blocks and through which a quantity of oxygen is discharged onto the slab surface to enable scarfing.
It is normally desirable to obtain a uniform depth of cut across the full width of the advancing workpiece, and this objective is often not achieved where the workpiece has a temperature variation, or a variation in metallurgical quality, across its width. More particularly, the temperature near one or both edges of the advancing workpiece is often lower than the temperature in the middle of the workpiece, and in this event the metal removal is reduced near the low temperature edges. Such a result is also possible where there is a variation in the metallurgical quality adjacent the side edges of the workpiece.
It is accordingly an object of the present invention to provide a metal scarfing apparatus having provision for overcoming the effects of variations in temperature or metallurgical quality across the width of the workpiece, and to thereby achieve a uniform metal removal depth of cut across the width under such conditions.
It is a more particular object of the present invention to provide a metal scarfing apparatus which is capable of separately controlling the metal removal depth of cut near the two side edges of the advancing workpiece, so as to overcome non-uniform temperature and quality effects, and so as to achieve a uniform removal across the width under such conditions.